Attitude stabilization of flexible spacecraft during stationkeeping maneuvers

This paper present s t h e a n a l y s i s and design o f r e a c t i o n j e t a t t i t u d e c o n t r o l system f o r a spacecraf t having l a r g e f l e x i b l e s a l a r a r rays . During t r a n s l a t i o n a l t h r u s t i n g maneuvers, t h e s o l a r a r r a y f l e x i b i l i t y s t r o n g l y i n t e r a c t s w i t h the Pulse-Width and Pulse-Frequency (PdPF) modulator. A simple t r a n s f e r f u n c t i o n model o f f l e x i b l e spacecra f t i s used f o r t h e p r e l im inary c o n t r o l design. The s t a t i c and dynamic charact e r i s t i c s o f the PWPF modulator a re discussed i n d e t a i l . Nonl inear s t a b i l i t y ana lys is i s performed us ing t h e descr ib ing f u n c t i o n o f the modulator. R e l a t i v e s t a b i l i t y margin w i t h respec t t o the l i m i t c y c l e c o n d i t i o n o f a s t r u c t u r a l mode i s used as a measure o f t h e non l inear c o n t r o l system robustness. The performance and s t a b i l i t y margin p r e d i c t e d by c l a s s i c a l s i n g l e a x i s design, a r e v e r i f i e d from t h e 3-ax is non l inear d i g i t a l s imulat i o n s .